Internal combustion engines combust fuel to convert the potential chemical energy therein to mechanical power that can be utilized for various applications. A common configuration of an internal combustion engine includes a combustion chamber formed as a cylinder with a reciprocal piston slideably disposed therein. Air is drawn into the cylinder by the downward motion of the piston with respect to the lengthwise dimension of the cylinder. Fuel is introduced to the cylinder either by direct injection, port fuel injection (PFI), or by being premixed with air that is drawn in. The piston reciprocally moves toward the top of the cylinder in a compression stroke compressing the air therein. The compressed air and introduced fuel are combusted forcing the piston again to move downwards in a power stroke. The engine can harness the forced motion of the piston for other work, such as propelling a vehicle, operating an implement, or running a pump or generator.
A variety of fuels can be combusted, including hydrocarbon-based fuels such as the traditional gasoline or diesel or alternatively liquid natural gas (LNG) or compressed natural gas (CNG). Ignition of the fuel in the combustion chamber may be induced by a sparkplug or glowplug, although in other embodiments the fuel may be susceptible to auto-ignition due to compression from the upward motion of the piston. In some embodiments, a pre-combustion chamber or prechamber may be located proximate to and in fluid communication with the main combustion chamber that serves as an additional volume in which a mixture of fuel and air is initially ignited to induce combustion in the combustion chamber. More specifically, an electrode disposed in the prechamber volume may ignite the fuel and air therein which then propagates through various ports to the main combustion chamber. Hence, the prechamber serves as a sparkplug or ignition element for the main chamber. One possible configuration for a prechamber is described in co-pending U.S. Patent Publication No. 2016/0053667 (“the '667 publication”), titled “Pre-Chamber Assembly for an Engine” and assigned to the assignee of the present application.
The '667 publication structurally describes a prechamber volume in communication with the main combustion chamber via a plurality of ports. Another channel introduces fuel to the prechamber volume via a valve mechanism. The '667 publication concerns designs for the channel and valve mechanism that achieve an optimal air-fuel mixture in the pre-chamber to improve the combustion process. Likewise, the present disclosure describes a prechamber assembly, serving as a sparkplug assembly for the main combustion chamber, that is designed to optimize the air-fuel mixture therein to facilitate the combustion process.